I missed the pilot, but saw the second episode, and found it a bit lackluster. They've set it in an interesting time, but in the episode I saw they're not using it in any sort of interesting way. It feels very modern (especially the female characters), like people at a dress-up party. I'll watch more, but I wasn't taken by my first taste (unlike Mad Men which hooked me right off when I stumbled into an early episode).
One thing they're definitely NOT capturing is the look of Las Vegas at that time. Their backlot settings don't look much like old Vegas, and their Fremont Street set is underpopulated, unconvincing, and about 1/3rd as dense with light as it should be at night. I remember that street from the late 60s, and it was a neon and bulb extravaganza for several blocks. This is what it REALLY looked like in 1960: